Field of the invention
The present invention relates, in general, to methods and apparatus for repairing openings in and immediately below a section of road or sidewalk pavement and, more specifically, to methods and apparatus for recycling pavement and base material in and immediately below an opening in a section of pavement back into the opening.
Cuts in the form of deep trenches are commonly made by utility companies in the pavements of roads and sidewalks to insert or repair underground utility lines. Problems with inadequately repaired or filled utility cuts frequently result in weakened sections of pavement which greatly reduces the useful life of such surfaces or requires the need for additional and costly repairs. All of these factors contribute to high road repair costs.
Various attempts have been made to devise methods and apparatus to address and overcome these problems associated with utility cut repairs in sections of pavement. Since merely replacing the excavated pavement material into the utility cut has resulted in an inadequate repair due to improper compaction, lack of pavement cutback, etc., filler material has been mixed with the excavated material to improve its characteristics in repairing utility cuts. This requires removal of the excavated material to a remote site for mixing with the filler material and the subsequent transport of the filler mixture back to the utility cut site. Such transport of material back and forth adds a significant amount to the cost of road repairs.
It has also been known to mix excavated material with a filler or new material utility cut site. Single or multiple vehicles are employed at the utility cut site to remove and mix excavated material from a road surface with sufficient quantities of filler material or new, fresh material before restoring the mixture to the utility cut. Still, a considerable length of time (i.e., 24 hours) is required for the restored material to set to a hardened state sufficient to carry loads. In addition, the asphalt or concrete pavement that has been broken out is not reused and must be removed from the site for disposal.
U.S. Pat. No. 4,815,819, filed in the name of the inventor of the present invention, overcomes the lengthy set-up time of such filler materials by filling the utility cut with a fluid, unshrinkable, settable, sub-grade base filler material to a desired depth below grade level and then heating the filler material to speed up the setting of the filler material in the utility cut to a hardened state within minutes instead of days. This enables a top layer of new asphalt or concrete to be immediately placed in the utility cut to complete the repair. However, this method still requires multiple vehicles to make a flowable backfill material for the utility cut which contribute to high repair costs. In addition, the filler material described in this patent is formed off site or away from the utility cut which again adds to repair costs and total repair time. What is needed is an in situ or at the site method and apparatus for removing, separating, mixing and reapplying a fluid filler material to a utility cut which can be performed directly at the utility cut site.
Other road repair and resurfacing methods and apparatus, typically those involving the repair of asphalt road surfaces, make use of single or multiple vehicles to remove the one to four inches of surface topcoat, to mix the removed material with a new coating material or fresh asphalt, and then to reapply the recycled and mixed material onto the road surface where it is heated and compressed by other vehicles and machines. However, such vehicles only remove the top few inches of the pavement and the underlying pavement bed and have not been devised for use with deep utility cuts extending three feet or more into the ground and which involve significantly greater amounts of rock, dirt, etc.
The pavement repair art is lacking a method or apparatus with combined means for performing all of the above-listed functions in repairing a utility cut in a section of pavement directly at the utility cut site by filling the utility cut with a fluid, unshrinkable, filler material which comprises a mixture of water, cement, flyash or the like, excavated material and/or the broken out asphalt or concrete surface material from the utility cut.
Thus, it would be desirable to provide a method and apparatus for removing, forming and reapplying a fluid, base material to a utility cut which is done directly at the utility cut site. It would be desirable to provide a method and apparatus in which all of the functions of removing, separating, mixing and restoring material to a utility cut is performed on one vehicle directly at the utility cut site. It would also be desirable to provide a method and apparatus for repairing a utility cut in a section of pavement which makes complete use of all of the material excavated from the utility cut.